Results Fifty infants completed PSG at 2.7±2.3 months; 56% were male, and 30% had a clinical diagnosis of Pierre Robin sequence (PRS)
or a syndrome. The majority of infants (75%) were reported to snore frequently or constantly, while 74% were reported to have
heavy or loud breathing during sleep. The frequency of parent-reported difficulty with breathing during sleep was 10% for
infants with isolated CL/P, 33% for those with syndrome, and 43% for PRS (χ2 16.1, p<0.05). All infants had an Obstructive–Mixed Apnoea–Hypopnoea Index (OMAHI) >1 event/h, and 75% had an OMAHI >3 events/h.
Infants with PRS had higher OMAHI (34.3±5.1) than infants with isolated CL/P (7.6±1.2) or infants with syndromes (15.6±5.7,
F stat, p<0.001). Multivariate analysis showed that PRS was associated with higher OMAHI (B 0.53±0.22, p=0.022), but the majority
of the variance for SDB was unexplained (constant B 1.31±0.55, p=0.024).

Conclusions The results highlight that infants across the spectrum of CL/P have a high risk of SDB symptoms and obstructive respiratory
events before palate surgery. Clinicians should enquire about symptoms of SDB and consider investigation with polysomnography
in all infants with CL/P.